Indonesians are officially the most smiley and pleasant people in the world. Most Indonesians initiate social contact with a smile, it is a sign that you are approachable. Smiling is very pervasive in Indonesian culture, so one must understand that it is a social requirements and it did not always means positive emotions.
However, Indonesian might reserve to smile when they are in an uncomfortable situation, confused, shy, embarrassed, or even felt offended. This sometimes give more complex it in social interactions in Indonesia.